Key Takeaways & Executive Findings
- •• Andalusite effectively replaces copper in resin-based brake pads, achieving high heat-fade resistance and environmental friendliness. • Optimal tribological performance is achieved with 320 mesh andalusite at 20% content, balancing hardness, impact strength, and wear resistance. • Andalusite addition enhances thermal stability, hardness, impact strength, and density of brake pads, improving medium-to-high temperature friction coefficient. • This study provides a viable path to eliminate copper from brake pads, reducing environmental pollution without compromising performance.
Abstract
The emission of copper-containing particulate matter during braking poses a threat to the natural environment, yet copper plays a crucial role in resin-based brake pads. Developing a copper-free brake pad with high heat-fade resistance has emerged as a significant current topic. This study employs andalusite-filled resin-based brake pads as a replacement for copper in brake pads. It investigates the effects of andalusite mesh size and content on the physical properties, mechanical properties, and tribological wear performance of the brake pads, and explores the wear mechanism of andalusite-filled copper-free resin-based brake pads. The results indicate that adding andalusite to the brake pads enhances their thermal stability, hardness, impact strength, and density, effectively improving the medium-to-high temperature friction coefficient and heat-fade resistance of the brake pads. As the mesh size of andalusite increases, the hardness of the brake pads also increases, while the impact strength initially increases and then decreases. As the weight content of andalusite increases, the hardness and impact strength of the brake pads gradually increase. When the andalusite mesh size is 320 mesh and the content is 20%, the brake pads exhibit good comprehensive tribological wear performance. The addition of andalusite not only increases the medium-to-high temperature friction coefficient of the brake pads but also strengthens their high-temperature friction surface. This study successfully replaces copper, which is harmful to the environment and costly, with andalusite in brake pads, obtaining a high heat-fade resistance metal-free resin-based brake pad.
1. Introduction
The braking system is a crucial factor in vehicle safety, and its importance is evident [1, 2]. As the actuating element of the vehicle’s braking system, the tribological performance of brake pads has a crucial impact on the entire braking system [3]. Resin-based brake pads are currently the most widely used automotive brake pads. In terms of its composition, resin-based brake pads are composite materials consisting of resin binders, reinforcing fibers, friction modifiers, and spatial fillers [4, 5].
In previous studies, metals and their compounds were often used as important components in brake pads [6–9]. Although the addition of metals can effectively enhance the tribological performance of brake pads, recent investigations have found that the metallic substances in brake pads are discharged as wear debris during the friction and wear process, existing in the form of tiny particles in the environment. These particles may cause respiratory system damage and pose threats to microorganisms, groundwater, and soil [10–14]. In 2010, the use of copper and related harmful substances as components of brake pads was strictly prohibited in the state of Washington, USA, for the first time by law [15]. Currently, the mainstream direction of research for new brake pads is how to achieve less or no metallization of brake pads while ensuring their excellent tribological performance [3, 16–18].
Resin-based brake pads offer several advantages, including low cost, convenient performance adjustment, a simple production process, and excellent overall performance [19–23]. Numerous studies indicate that copper plays a pivotal role in enhancing the tribological properties of brake pads. Copper boasts excellent thermal conductivity and good ductility, making it an effective high-temperature solid lubricant [24]. Hence, the incorporation of copper into brake pads can significantly enhance heat-fade resistance, reduce vibration and noise, and lower wear rate [25–27]. In recent years, numerous scholars have conducted extensive research on the development of copper-free resin-based brake pads, achieving notable progress. Studies have used waste foundry sand [1], fly-ash cenospheres [2, 28], and cement bypass dust [29] to replace copper in resin-based brake pads.
Loading authentic research manuscript (Pages 1–5)...
Kaikui Zheng, Zijing Min, Fawang Zhang, Zhiying Ren, Youxi Lin (2025). High Heat-fade Resistance, Metal-free Resin-based Brake Pads: A Step towards Replacing Copper by Using Andalusite. Chinese Journal of Mechanical Engineering. https://doi.org/10.1186/s10033-025-01310-x
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the main objective of this study?
The main objective is to develop a copper-free resin-based brake pad with high heat-fade resistance by using andalusite as a replacement for copper, thereby reducing environmental pollution without compromising tribological performance.
How does andalusite affect the properties of brake pads?
Andalusite enhances thermal stability, hardness, impact strength, and density of brake pads. It also improves the medium-to-high temperature friction coefficient and heat-fade resistance, contributing to better overall tribological performance.
What are the optimal conditions for andalusite in brake pads?
The optimal conditions are an andalusite mesh size of 320 mesh and a content of 20%, which yield good comprehensive tribological wear performance.
Why is replacing copper in brake pads important?
Copper in brake pads is harmful to the environment as it is released as particulate matter during braking, causing respiratory issues and threatening ecosystems. Regulations, such as in Washington State, USA, have prohibited its use, driving the need for eco-friendly alternatives.
What is the significance of this research for the automotive industry?
This research provides a viable, cost-effective, and environmentally friendly alternative to copper in brake pads, enabling manufacturers to comply with regulations while maintaining high performance and safety standards.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.